Ok, I reacently picked up two LM4780 chips from ebay and thaught that I would make a amp with a bit more power then my lm3875. Is there a good idea to use one bridged chip per channel with a 4 ohm load? Or do I need to use them in parallel config instead?

And one other thing i might add. Do you think the regulated powersupply by CarlosFM using lm338 could be used for this settup aswell, though with a 300VA trafo?

Ok, but since I already got that regulated powersupply for my lm3875 I was hopping I cpould use it for my 4780 instead. But is the 5 amperes that the lm338 is good for enough to drive the two chips in parallel config?

If you can lay your hands on 2x 50w zener diodes cheep, you could try the regulated power supply I used for my paralleled LM4780 amplifier. (I recently posted 2x photos in the chip amp photo gallery)
It is very simple (extra 3 parts) but you would also need 2 separate windings on your transformer or 2x transformers (as there are no equivalent negative regulators)
It uses the 5A (7A-limit) LMS 1585-1.5v regulator with a 5k trimmer in the ground lead to set the output to 35v.
An 8.2v/50w zener diode across the LMS 1585 limits its maximum differential to the zener voltage, (Under the regs 13v limit).
The LMS 1585 is then protected from capacitor charging inrush, and placing a short on the PS and turning on the power only blows my 5A DC protection fuses (No Damage to the PS)
With full power both channels into a 4ohm load it can lower the PS input voltage to below the output voltage (I have 43v input) so the PS becomes unregulated at this point.
But as the LMS 1585 is a low dropout regulator, only 1.1v is lost so almost the full PS voltage is still available although now unregulated.
It is essential to have large capacitors (I used 10,000uf) on the input and output of the regulator to handle the peak currents.
Remember the output current to the speaker is shared from both the positive and negative supplies (3A @ 2x35v = 210W)
I find using the amplifier to clipping point listening to music (very loud) and monitoring the PS and output on a dual trace scope the PS never looses regulation.
I salvaged the 50w zeners from some old power supplies given to me.

Ok, thank you all very much for the info. But if
"a 4ohm load will draw about 6Apk from an AC supply of 24Vpk. That's equivalent to 72W from the pair of chipamps so they should be able to cope." then shouldnt it draw less with my closer to 30 VAC supply? It´s not that important to me to have a regulated supply but it would be nice to compare the two options